This class is very dirty. We... clean it before the ...

★ Expressing Obligation and Modals

“This class is very dirty. We… clean it before the teacher comes.” The best answer to complete the sentence is…

A. should

B. must

C. must not

D. should not

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Choose the correct option to complete the sentences:

Expensive products ______________ be good quality for people to buy them.

A. don’t need to

B. must